This National Weather Service map, released at 2:29 p.m., shows the projected average snowfall amounts. Some areas could get less, while some could get more.

By Martin Finucane and John R. Ellement, Globe Staff, and Katherine Landergan, Globe Correspondent

A major nor'easter that blanketed the state with snow is winding down tonight after causing spinouts and fender benders on the roads, delays and cancellations on trolleys and trains, a virtual shutdown of Logan International Airport, and tens of thousands of power outages.

Governor Deval Patrick urged people late this afternoon to continue to stay off the road tonight as the storm, which was expected to drop as much as 30 inches of snow in some areas of Western Massachusetts, eased out of the area. Even tomorrow, he said, drivers should exercise caution as workers continue to clear the roads.

"Fortunately, blessedly, there have been no serious injuries," he said.

Boston and a number of other school systems announced this afternoon that they would close school on Thursday for a second day, a move sure to lighten kids' hearts but leave their parents scrambling for child care arrangements. Boston also said it would extend its snow emergency parking ban to 9 a.m. Thursday.

Patrick said that not only was there more snow than originally forecast but in the eastern portion of the state it was wetter and heavier, which raised the likelihood of power outages.